Just go to Google and type in "php content management tutorial" and it will show you some great tutorials right in the first 10 matches.
PHP is great for content management and can certainly do a lot of things including image manipulation, articles and resource management, file handling etc. Some great CMS' are made with php. One great site for trying some of the popular ones for free and WITHOUT needing to install them is at the following address...
OpenSource CMS WebsiteThere you can try them up by selecting them from the menu on the left and simply logging in using the provided demo username and password. They are reinstalled automatically every two hours which is why they can let the public play around with them. It is a great site and should give you a realistic idea of what they can do.
Enjoy!